1. Field of the Invention
The present invention relates to a super resolution information storage medium, and more particularly, to an information storage medium that includes a recording mark of smaller magnitude than a resolving power of a reproduction beam in which information is recorded and from which information is reproduced and that has an improved carrier-to-noise ratio (C/N) and improved stability of signal reproduction.
2. Description of the Related Art
Optical recording media are used as information storage media with respect to which an optical pickup unit records and/or reproduces information in a non-contact way. Due to industrial development, the information storage media require a higher recording density. For this purpose, optical recording media, which have recording marks of a smaller magnitude than a resolving power of a laser beam so as to produce a super resolution phenomenon, have been developed.
When a wavelength of a light source for reproducing information from a recording medium is λ and a numerical aperture of an objective lens is NA, λ/4NA is generally a reproduction resolving limit. In other words, since a beam irradiated from a light source cannot distinguish a recording mark of a smaller magnitude than λ/4NA, information reproduction is generally impossible.
However, a super resolution phenomenon may occur, i.e., information may be reproduced from a recording mark of a larger magnitude than the reproduction resolving limit. Thus, the analysis of causes of and research and development on such a super resolution phenomenon are in progress. According to the super resolution phenomenon, it is possible for information to be reproduced from the recording mark of a larger magnitude than the reproduction resolving limit. Thus, a super resolution recording medium may substantially satisfy the demands for high density and large capacity.
To commonly use such a super resolution recording medium, the super resolution recording medium must meet basic recording and reproduction characteristics. Of the recording and reproduction characteristics, a C/N and the stability of signal reproduction are important. In particular, compared to a general information storage medium, a super resolution information storage medium uses recording and reproduction beams having relatively high powers. Thus, the realization of such a C/N and the stability of the C/N is a major task for the super resolution recording medium.